Process of manufacture of alkaline and earthy-alkaline nitrates.



P. A. GUYE, G. DARIER & A. VAN VLOTEN. PROCESS OF MANUFACTURE OF ALKALINE AND EARTHY ALKALINE NITRATES.

APPLICATION FILED JUNE 25, 1910.

36,6 1 1 a Patented Aug. 27 1912.

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I I waaml'ia PHILIPPE nuousrncorn mm ononens outrun, or GENEVA, swzrznmznnn, AND

' mu 'vno'rmi, OF HAARLEM, NETHERLANDS.

'Pnoonssor'qvmawr'nommri or ALKALINE ANn'EnnrnY-AnKALINn m'rnnrns.

Specification of ne sman, Patentedfiuggj, 1912..

Application ifiled June 25, 1910. Serial ,No. 568,838.

To-aZZ whom it may concern: v

Beit known that we, PHILIPPE .Aueus'rc Gum and Grosses DARIER, citizens of the; Republic ofSwitzerland,.residing at Geneva, 1 Switzerland, andAsLnAnar VAN VLOTEN, asubject of thdKingdem of the Netherlands, residing at Haarlem, Netherlands, have inven'ted new and useful Improvements in Processes of Manufacture of ,Alkaline' and Earthy-Alkaline Nitrates, of which the following is a specification, j It has been Jxnown fora long time :that, in order 'to completely convert alkaline chlorids: into corresponding nitrates, it is necessary to 1 heat them several times with an excess of 7 concentrated nitric acid (of. Firescnius Quantitative Analysis, "Paris, 1909, L, 160-162), Under these conditions, aqua regia (nitrohydrochloric acid) is disengaged, at, the same time that a large part vof the nitric acid in vexcess decomposes :into oxids ofnitrogen ordistils the same is true when calcium 1 chlorid is b'ein converted into nitrate 03E cal-, cium. In stu ying more closely these *vari-j ous transformations, ,the following observa-' tions havefbeen made and have led to the process which 'formslthe object of the present" application for patent. 'These experiments have shown, first, that even with an :excess' of from and ,per cent. of nitric acid (containing 36 to 37% NOQH), relatively the theoretical proportions, a portion of the? sea sa'lt (4 to 12%) still escapes from the transformation; with more dilute acids* slightly more favorable results have been 010- 5 tained. IEf,--on the other hand, a great ex cess of-salt is employed, only about fl ths of the nitric acid is converted into nitrate. With chlorids of potassium-and calcium reacting in theoretical proportions with nitric acid, at the same concentrations, the results are more favorable; :about f' ths oif the nitric acid employed is obtained in the :form of nitrates .of potassium .or of calcium. These, results have led to a still closer study of the causes which' limit :the -.conversion of the: nitric aoidinto nitrate of sodium whensaid;

acid ,ismusedito react \withsea salt. v [t; vcas first determined that nitric acidofwveak concentrations (below 35 per cent.) gave better results, and then that the conversion is min-e vcomplete when the operationis-conducted at a lower temperature, and when the nitric acid is maintained at a certain degree of dilution as long as theelimination of hydrochloric acid lasts; in practice, this result is obtained by heating, with precautions, the products in reaction, while imaintainingthem under. a pressure less than atmospheric, res this sure. To give an idea of the-efficacy method of operation, some results obtained are ,given .below by way of example, .calcu-' lated in nitric. acid vconverted into nitrate-of d m by reaction .w1th sea salt:

i d i 7s 7 807 o c ..\.....u T6 Tmxl emtureof evaporation. so e. -seo. 70 0. 40%0. f It will be seen from these results that a portion of the nitric acid always escapes rom the -,convers1on 1t Issues from the ap or in the form of nitrous vapors and aqua .70 .para'tus either in the form of freenitric acid I regia (containing probably oxids of nitrogen N0 N 0,, NO and the gas NOCI) I both cases these roducts are mixed with an excess of 'hydroc 'loric acid and water; the

proportioniof nitrous vapors and, of aqua reglaIbecomes negligible, if the reaction 1s conducted at a sufiiciently low temperature. The products thus disengaged cannot be used as they are; in order :to render them utiilizable, it is advantageous to cause them to ;pass over a column of solid chlorid of sodium, in which there is formed a fresh-quantity off nitrate,,so that, at the exit from the said colunmythere' is-recovered,'by condensation ofthe gaseous product, anaqueous solu- --tion, more or less diluted, of hydrochloric acid ;containing only traces of nitricvaoid, To facilitate the recuperation of; the nitrous vapors, the introduction of a small'quantity of air or of oxygen intofthe-columnof recuperation :is useful. There has therefore been based upongall the new observations mentioned above, saqprocess of converting aqueous znitricmcid into alkaline.- :or earthy alkaline nitrates, consisting in causing the aqueous acid to react with the corresponding chlorids, the process being characterized by: (1) the employment of dilute nitric acid of a concentration lower than 35 per cent. NO I-I, maintained as far as possible at these feeble concentrations during the entire duration of the operation; (2) conducti'n'gfthe operation at a temperature lower than 80 recovered in the principal receptacle in which the reaction takes place, about 93 per cent. of the, nitric acid in the state of nitrate of soda; the 7. per cent. remaining is recovered, almostintegrally, at the bottom of the column of chlorid of sodium in the form of solution of nitrate of sodium, containing a little chlorid; finally the aqueous hydrochloric acid is condensed in large part to a density approximately equivalent to that of the nitric acid employed. Asfor the crudenitrate of sodium obtained, it is easily separated by crystallization from the chlorid which accompanies it.

As a modification, the operation may also be carried on without producing a vacuum,'by maintaining the products in reaction at a temperature below 80 0., and by carrying over, by a current of air, the hydrochloric acid formed; the latter, charged with vapors of nitric acid or of its products of decomposition, passes into ap-s paratus containing solid salt which fixes, in the form of nitrate, the greater part of the nitrated products carried over this method of operation complicates slightly the recuperation of'the hydrochloric acid.

In the accompanying drawing we have illustrated, diagrammatically and conventionally, an apparatus suitable for practising our invention, where sodium chlorid is the alkaline chlorid to be converted into the corresponding nitrate.

'In the drawing, Figure 1 is a top plan view, and, Fig, 2 a longitudinal sectional view of such suitable apparatus.

In the said drawing the referenceletter A designates a vessel which, after the desired pressure, or vacuum (the terms being often used as convertible) has been obtained by means of the vacuum pump P, is

heated, preferably by steam, or otherwise suitably, into which is introduced the nitric acid and the sodium chlorid, through the funnel B which is provided with a controllable valve 0". In this vessel ,we understand the following reaction takes place:

The letter D designates a condensation tower interposed between the vessel A and the chlorid tower T. This condensation tower serves to retain the liquid products carried of]? from the vessel A by, the vapors of water and of hydrochloric acid, the froth, etc, conducted thereinto by means of the conduit C. From the condensation tower D, the vapors, which consist of a mixture of water vapor (steam), gaseous hydrochloric acid, and a slight quantity of unconverted nitric acid, and of nitrous vapors in very small proportion, pass through the;

conduit 0 into the chlorid tower T, upon the plates of which (shown in dotted lines) solid sodium clilorid has been disposed. The nitrous products are retained in this tower. The products issuing from the tower T are a mixture of vapors of water and hy drochloric acid and they are conducted by the conduit 0 into the condenser E. The condensed product is collected through the stop cock R The acid vapors which escape condensation pass through the towers F and F being conducted by conduits C G", C. These towers F and F contain either water or milk of lime to avoid sending out into the atmosphere any gas which may still contain free hydrochloric acid.

The letters R, R, R R It and R designatethe valved outlets for the vessel A, condensation tower D,"chlorid tower T, condenser E and the towers F and F.

The letters S, S, S S, S and S de ignate pedestals for suitably supporting the parts as shown.

Having thus described our invention, what we claim and desire to secure by United States Letters Patent is:

1. A process for manufacturing nitrates consisting in subjecting alkaline or alkalineearthy chlorids to nitric acid diluted atleast to 35% NO H, maintaining such degree of dilution as far as possible, and carrying on the reaction of the acid on the. salts at a temperature not exceeding 80 C.

2. A process for manufacturing iiitrates consistin in subjecting alkaline or alkalineearthy c lorids to mtric acid diluted at least to 35% NOJ-I, maintaining such degree of dilution as far as possible, and carrying on the reaction of the acid on the salts least to 35% NO H, maintaining such degree of dilution as far as possible, and carrying on the reaction of the acid on the salts at a temperature not exceeding 80 C. and under a pressure lower than 300 mm. of mercury, and conducting the vapors into the presence of a solid salt of the nature of the chlorid treated.

In testimony whereof we have hereunto set our hands in presence of two subscribing witnesses.

Witnesses for Philippe Auguste Guye:

DR. GAUDIsET, E. CARDOSO.

'Witnesses for Georges Darier:

' M. MERLING,

L. H. MUNIER.

Witnesses for Allart Van Vloten:

W. A. TAKEN, HY. H. MORGAN. 

